1. Field of the Invention
The present invention relates to an organic light emitting display (OLED) device (or organic electroluminescent display device), and more particularly, to a system on panel (SOP)-type emission driver generating an emission control signal to control emission of pixels arranged in a pixel portion, and an organic light emitting display (OLED) device having the same.
2. Description of the Related Art
When an organic light emitting display (OLED) device is constructed to have a large screen, the dimensions of an OLED display panel for a glass substrate are limited due to fabricating process limitations. Also, if the screen is large, there is a greater probability of a defect occurring somewhere on the screen and thus a reduction in yield is generally unavoidable, and it is difficult to obtain uniformity across the screen.
As a solution to the above problems of the OLED display device, a tiling technique was developed. In the tiling technique, a plurality of OLED display panels are bonded like tiles to form a single panel.
Each of the OLED display panels includes a plurality of pixels to display an image like in a conventional OLED display device. In each of the OLED display panels, a scan driver applies a scan signal to enable the pixels, and a data driver applies a data signal to the selected pixels. Also, an emission driver applies an emission control signal to each of the pixels in order to control the exact programming of the data signal and the time taken for an emission operation.
As described above, the scan driver, the data driver, and the emission driver, which transmit various signals to drive the OLED display panels, can be electrically connected to each of the OLED display panels in various manners.
For example, the scan driver, the data driver, and the emission driver may be mounted as chips on a tape carrier package (TCP) that is bonded and electrically connected to each of the OLED display panels. Alternatively, the drivers may be mounted as chips on a flexible printed circuit (FPC) or a film that is bonded and electrically connected to each of the OLED display panels. The latter technique is referred to as a chip on flexible board (or chip on film) (COF) technique. In another method, the drivers are directly mounted on a glass substrate of the OLED display panel. This method is referred to as a chip on glass (COG) technique.
These methods are costly and complicate modules because the drivers should be separately designed and electrically connected to one another. To overcome these drawbacks, a system on panel (SOP) technique has been developed recently. Also, there have been attempts at designing a pixel portion, scan and emission drivers and/or a data driver in each OLED display panel, in order to construct all systems in the OLED display panels.
In the OLED display device using the tiling technique, when each OLED display panel is formed as an SOP type, it is easy to bond the OLED display panels to one another. Also, the SOP technique enables the area of drivers to be reduced and cost and labor for designing integrated circuits (ICs) of the respective drivers to be saved.
However, in order to develop the SOP-type OLED, it is necessary to consider many internal circumstances and conditions of the OLED display panels, such as a driving frequency and electron mobility of the data driver and/or the scan and emission drivers. Up to present, it is still difficult to design the data driver within a panel because the data driver needs a high driving frequency.
Accordingly, the data driver is formed as an IC using complementary metal oxide semiconductor (CMOS) technology and connected to the OLED display panel, while the scan driver and/or the emission driver are formed within the OLED display panel.
Therefore, there is a need of a simple circuit construction in which an SOP-type scan driver and emission driver can be driven in the OLED display panel.